This invention comprises a vibration and pressure transducer and a method for making it, and especially a pressure transducer, and method for making it, in the form of a film, utilizing a poled polymeric film as a sensing element.
Transducers for sensing pressure waves are generally of the piezoelectric ceramic type. The size of these transducers is sometimes a handicap; either smaller or larger devices may be desired. Furthermore, these devices may be relatively expensive. It would be very desirable to have a pressure transducer which may be made in any shape or size that is useful for a particular application and which is very inexpensive to manufacture.
This type of transducer, or sensor, may be made from materials whose molecules are dipoles which can be treated to have a permanent net orientation. Such materials may be polymers and will be known as permanently polarizable polymers. By aligning many of the dipoles which, in the untreated state, are randomly oriented, the surfaces of a polymer film can be oppositely and permanently charged, i.e., the film has a permanent dipole moment. Pressure on the film disorients these aligned dipoles and produces changes in the surface charge detectable as voltage changes.